1. Field of the Invention
The present invention relates to an RF receiver, and more particularly, to an RF receiver recovering timing offset by shifting determination slots in response to timing offset in response to when sampling a signal.
2. Description of the Related Art
Recently, a ubiquitous communication environment that allows users to access networks from anywhere at anytime has been proposed. A study on small-scale wireless communication systems, wireless personal area networks (WPAN), ubiquitous sensor networks (USN), radio frequency identification (RFID), and the like rather than cellular networks and large-scale communication networks, has been actively made.
Among the above-described communication systems, the WPAN and USN require a reduction in size, low cost, and low power consumption as well as communication performance. Therefore, it is difficult to directly apply high performance and high cost components used in the general cellular communication systems or the general wireless personal area networks to the above-described wireless communication systems.
On the other hand, when cheap components are used to reduce costs, great frequency error or phase error may occur. Therefore, there is a need to find out a solution to this problem.
Hereinafter, an RF receiver used in the wireless personal area network according to the related art will be described with reference to the accompanying drawing.
FIG. 1 is a configuration view illustrating an RF receiver used in a wireless personal area network according to the related art.
Referring to FIG. 1, an RF receiver 10 according to the related art includes a preprocessing unit 11, a differential operation unit 12, a correlation unit 13, and a demodulation value estimation unit 14. The preprocessing unit 11 samples and digitalizes an analog received signal. The differentiation unit 12 delays the digitalized received signal and differentiates the delayed signals. The correlation unit 13 correlates 16 code sequences with the differentiated signals and sequentially outputs correlation values. The demodulation value estimation unit 14 detects a maximum value among the correlation values and determines a PN code sequence corresponding to the detected maximum value as a symbol of the received signal.
In the above-described RF receiver 10 according to the related art, timing offset occurring when the analog received signal is sampled is reflected in output time of the correlation values. When the correlation values are sequentially output, the timing offset is continuously reflected in the correlation values. Therefore, the RF receiver 10 determines a wrong PN code sequence but not the PD code sequence corresponding to the maximum value as a symbol of the received signal according to the related art, which may cause a reception error.